A central door-lock system normally has at each vehicle door latch a servoactuator basically formed as a reversible servomotor connected through an appropriate link to the respective door latch. This servoactuator is normally connected in parallel to the inside door lock so that it can lock and unlock the door. All of the servomotors are in turn connected to a central switch that is normally incorporated with the inside and outside door locks of the driver's door. Thus when the driver locks or unlocks his door all of the other doors of the vehicle are automatically locked or unlocked. In this manner the driver is spared the effort of walking around the car to lock or unlock the passenger doors.
My above-cited copending application Ser. No. 132,977 describes a central vehicle door-lock system wherein the servoactuators each include an actuator operatively engageable with the respective door-latch detent and displaceable between lock and unlock positions, an operator engageable with the actuator and movable between lock, unlock, and antitheft positions, and a lock pawl displaceable by the respective operator only in the lock position of the respective actuator and in the antitheft position of the respective operator from a freeing position permitting displacement of the respective actuator from the respective lock to the respective unlock position into a blocking position preventing displacement of the respective actuator from the respective lock to the respective unlock position. Link means is provided connected between the detents, actuators, and operators for joint displacement of same between the lock and unlock positions. Each servoactuator has a servomotor connected to the respective operator for displacing same between the respective unlock, lock, and antitheft positions. Control means is connected to the servomotors and includes a switch displaceable between an unlock position for displacing the operators into the respective unlock positions, a lock position for displacing the operators into the respective lock positions, and an antitheft position for displacing the operators into the respective antitheft position. Thus when the switch is in the antitheft position the mechanisms of the door latches cannot displace the detents into the respective unlock positions, as the lock pawls are retaining the operators in the lock position to in turn retain the actuators and detents in the lock positions.
With such a system, therefore, even if for example a window of the vehicle is forced open or one of the vehicle door locks is operated, the respective door cannot be opened because the respective servoactuator will be positively holding the respective door detent in the lock position. In a vehicle with inside door buttons, therefore, these buttons will be locked in the down or lock position so that the door cannot be opened from inside or outside when the system is in the antitheft position. Of course in the lock position of the control switch any of the door latches can be operated by its respective inside or outside door lock independently of the other latches.
My second above-cited application relates to an arrangment having door latches each of which normally has a detent lockingly engageable with a bolt or pin on the respective doorpost and displaceable between open and closed positions respectively allowing the door to be separated from the respective doorpost and securely holding the door to its respective post. Mechanism inside the latch allows this detent to be operated by inside and outside door handles, and this mechanism itself is normally controlled by inside and outside door locks that allow the inside and outside door handles to be uncoupled from the detent. Thus when the door is locked it cannot be opened from either the inside or outside handle, and this locking can be carried out either by means of an externally accessible key-operated door lock or by means of an internal lock button or lever. Each such latch in a central system is associated with a respective servoactuator as described above.
My application Ser. No. 132,978 cited above is aimed at a central door-lock system having door latches of the type described immediately above, but having a detent and a manual door-opening handle as well as primary and secondary latch members. The primary latch member is connected to the handle and is connectable to the detent and movable between a lock position preventing the handle from displacing the detent between the open and closed positions and an unlock position permitting the handle to displace the detent between the open and closed positions. The secondary latch member is displaceable between a lock position urging the primary latch member into the respective lock position, an unlock position permitting the primary latch member to move between the respective lock and unlock positions, and into an antitheft position positively holding the primary member in the respective lock position. The servoactuators each have an actuator element connected to the respective secondary latch member and a servomotor that displaces the respective secondary latch member via the respective actuator element between the respective lock, unlock, and antitheft positions. A central switch is connected to all of these servomotors to operate same jointly and thereby jointly displace the secondary latch members between the respective positions.
Thus in accordance with my earlier invention the secondary latch member merely urges the primary latch member into the lock position, so that, even if the central lock system is in the lock position so that all doors are locked, it is possible to manually unlock any one of the doors without having to unlock them all, this door however automatically relocking itself the instant pressure is released from the inside or outside door lock. In the antitheft position, however, the secondary member positively holds the primary member in the lock position so that it is impossible to open the door latch either from inside or outside.
My above-described systems have various advantages and disadvantages. The use of a nut and threaded spindle connection for displacing the operator has a high mechanical advantage, but is relatively slow. On the other hand the directly coupled systems present the danger of being broken if they are forced either intentionally or inadvertently.